The invention deals with a low-voltage power cable [according to the preamble of claim 1].
Low-voltage power cables according to the invention form, in particular, the current-conducting building group of a system, that, depending on the number and kind of its accessories, consists of several power users and if necessary, of a transformer, that transforms the line voltage into the low voltage range. Preferably it deals, in the case of the low-voltage power cable according to the invention, with the supplying of current to a lighting arrangement, whose light fixtures are fitted with halogen lamps. Such systems are mounted on large surfaces, for example, over ceilings, in order to illuminate the room itself or certain objects in the room.
With these and other systems the low-voltage power cable according to the patent, along with its holders which hold it on the mounting surface, takes over the function, beyond that of guiding the current, of removing the stresses, especially those due to the weight, coming from the directly mounted structural groups. The mentioned lighting system deals therefore essentially with the mounting of light units. Due to its rectangular cross-section, the low-voltage power cable develops its greatest load-bearing capability in the direction of the long axis of the rectangular cross-section, corresponding therefore in space to the y-axis. With respect to a ceiling-mounted system, the longer sides of the conductor cross-section run perpendicular.
The wire cloth bands, which constitute the current phases of such a system, are electrically isolated by means of insulators. However, through their mounting on the insulator they form a material bond with the insulator, through which the insulator, made of a dielectric material, gains increased load-carrying strength from the wire cloth. The wire cloth bands are relatively thin, but they offer, nevertheless, a relatively low electrical resistance. For this purpose they can be bonded over their whole surface to the insulator, for example they can be glued.
Such low-voltage power cable for lighting arrangements, as such, are known (DE-GM 89 12 824). The power cable forms a band that is flexible in all directions. Here the insulator has a certain outline on its rectangular surface, on whose longer sides the wire cloth bands are fastened, which bands therefore lie with their edges free and projecting out from the outline of the insulator. The current-carrying band is flexible, and must therefore be fixed at both ends, as well as being held in an upright position at one end by a insulating anchoring means. The twisting rigidity of this band is nevertheless comparably weak. That necessitates high tension for anchoring the cable. In spite of that, the suspended band lengths are small. Heavy accessories, for example light units arranged in narrow spaces, require a multiplicity of band holders. Furthermore the straight run-lengths are in general predetermined. When the system, due to conditions at the site, requires sections of band which bend toward each other in the plane of the system, the band must be lead through anchored curved pieces at the vertices of the bends and corners. That greatly reduces the possibilities of configuring such a system.
The known low-voltage power cable, because it shows only two current phases, is not suitable for extensive lighting systems, for with such systems possibly such a large number of accessories are required that the suspended wire cloth bands are not safe to touch.